1. Field of the Invention
This invention relates to a method of manufacturing a nonwoven fabric constituting a substitute for a textile fabric, and to the product manufactured thereby. More specifically, this invention relates to a method for manufacturing a disposable, randomly arranged, intermingled cellulosic fiber sheet which has sufficient strength and absorptive capacity to serve as a disposable textile replacement fabric for industrial wipers, household wipers, and the like, and to the product produced thereby.
2. Description of the Prior Art
Considerable effort has been devoted to providing inexpensive, disposable, nonwoven fabrics to be used as a substitute for textile fabrics. Such a fabric is particularly desirable for use as an industrial or household wiper, wherein disposability has become an attractive feature. To meet market demands in this field, the disposable fabric must be absorbent, strong in both the wet and dry state, capable of retaining liquids, and low cost. From an economical standpoint, one of the most attractive approaches in fabricating a nonwoven textile replacement fabric is to incorporate a substantial amount of wood pulp fibers into the fabric. Although an untreated wood pulp batt is highly absorbent, it unfortunately possesses low cohesive strength in both the wet and dry state, low forces of capillary attraction, and an inadequate ability to retain fluids which are absorbed.
In U.S. Pat. No. 3,017,304 Burgeni discloses applying controlled amounts of moisture to the surface of a wood pulp batt, or web, and thereafter applying pressure within controlled limits to form a densified, highly compacted cellulosic fibrous layer which is integral with the remainder of a loosely compacted, fibrous absorbent body of the web. This treatment increases the cohesive strength of the batt, increases the capillary forces in the batt and enhances the fluid retentivity of the batt. Although this treatment may be adequate for applications wherein the batt is wrapped in an outer protective, or stabilizing cover, it is not adequate to produce a sheet product having the strength, stability and durability to be considered a self-sustaining substitute for conventional textile fabrics utilized as household wipers, industrial wipers, and the like.
British Pat. No. 401,149 discloses a process for producing a nonwoven material having the properties of deerskin, in which loose cotton fibers are formed into a fleece strip which is laid in a zig-zag arrangement on a reciprocating table, one layer on top of another, until a sufficiently thick structure is obtained, alternate layers being arranged cross-wise. The structure is then wetted and pressed in a calender, after which a binder having an india rubber emulsion containing vulcanizing ingredients as a base and being suitably colored, is sprayed onto the structure under pressure. The structure is then oven dried, until vulcanization sets in and completes the process. The above-described process produces a leather-like material which does not possess the absorptive rate or capacity characteristics to permit its use as a substitute for a textile fabric in household and industrial wiping applications.
In U.S. Pat. No. 2,955,962 Engdahl discloses a nonwoven dust cloth which is made from either 100% viscose rayon fibers or 40% thermoplastic cellulose acetate fibers and 60% non-thermoplastic viscose fibers. These dust cloths have an extremely low basis weight, i.e., on the order of 1/2 oz/yd.sup.2, and will not possess the absorptive capacity desired for use as household or industrial wipers. Additionally, the dust cloths disclosed in the Engdahl patent are manufactured from a substantial percentage of viscose rayon textile fibers, and therefore, the resulting product is considerably more expensive than one containing a substantial amount of wood pulp fibers in lieu of rayon textile fibers.